In recent years, consumers have demanded increased access to copyrighted content (e.g., movies, music, books, etc.) in digital form via cable television, satellite broadcasting, the Internet, digital versatile disks (DVD), compact disks (CDs), etc. Because this valuable content is provided in a digital format at high quality levels, and because digital data is highly reproducible, pirates have frequently sought to usurp the profits of the copyright holders by making and selling unauthorized copies of this digital content. Efforts have been underway to provide mechanisms for limiting unauthorized copying and distribution of this copyrighted content to ensure the copyright holders are rewarded for the consumption of their intellectual property.
To address some of these concerns, a group of technology companies recently developed Digital Transmission Content Protection (DTCP) technology. DTCP provides a protocol in which various cryptographic techniques are employed to prevent unauthorized copying and distribution of digital content. In DTCP, copy control information (CCI) is carried by the digital content. The CCI specifies the conditions for copying the associated content. For example, digital content may be classified by the CCI such that (a) the content may be freely copied (no authentication required to access the content and no encryption needed to transmit the content), (b) the content may never be copied, or (c) one generation of copies may be made of the content and then classified as (d) no more copies. To access digital content protected by DTCP, a device must be authorized (i.e., have access to the decryption key(s) used to unlock the content). If an authorized device is instructed to copy the digital content, the authorized device will read the CCI information and abide by the criteria set therein. Thus, the CCI information ensures that all DTCP content carries a set of rules governing reproduction of that content, which has the salutary effect of preventing pirates from purchasing one legitimate copy of copyrighted content and then making multiple unauthorized copies.
While DTCP is a significant advance in controlling distribution and copying of digital content, the recent proliferation of digital technology in the home environment presents additional challenges to controlling copyrighted materials. For example, it is becoming more common for a home to include a home Internet Protocol (IP) based network in which a number of entertainment and/or information devices (e.g., a computer, a DVD player, a digital or analog video recorder, a television, etc) are networked. Thus, it is frequently desirable to transfer copies of copyrighted material from device to device within the home. Often, the home network is coupled to the Internet, thereby raising the possibility of transferring unauthorized copies of copyrighted material from one Internet Protocol home network to another.
Efforts are underway to apply DTCP technology to the IP home network context. However, it is desirable to permit an authorized licensee of digital content to transfer that digital content from device to device within the home network. Thus, a significant impediment to applying DTCP to the home IP based network comprises permitting movement of content within the home IP network, while preventing distribution of that content beyond the home via the Internet.